Configurable dual vacuum tube triode amplifier

ABSTRACT

Disclosed is a configurable dual vacuum tube triode amplifier. The amplifier comprises two vacuum tube triodes and a user configurable switching component. The user configurable switching component can be positioned into at least a first position and a second position to modify an arrangement of the two vacuum tube triodes to provide varying tonal characteristics of the amplifier. Positioning the user configurable switching component in the first position arranges the two vacuum tube triodes in a cascode configuration to achieve a tonal characteristic of a vacuum tube pentode. Positioning the multi-position user switch in the second position arranges the two vacuum tube triodes in either a single vacuum tube triode configuration to achieve a tonal characteristic of a single vacuum tube triode operating alone or two vacuum tube triodes operating in a parallel configuration to achieve the tonal characteristics of two vacuum tube triodes operating in parallel.

TECHNICAL FIELD

The present disclosure generally relates to the technical field ofvacuum tube amplifiers. In particular, the present disclosure relates toa configurable dual vacuum tube triode amplifier.

BACKGROUND

In the field of electric guitar amplification, history plays animportant role. For many players, the ability to reproduce guitar tonesmade iconic by bands such as the Beatles remains a high priority. Thisis true not just for “cover” or “tribute” bands, but for a sizablesegment of musicians. The guitar sounds produced by now-old amplifiersare definitive and classic and the desire to achieve these tonespersists today.

One example of these classic amplifiers is the British made VOXamplifiers of the 1960s popularized by the Beatles, The Rolling Stones,Queen and many others. The best of these amplifiers were two-channelamplifiers where one of the channels utilized an EF-86 pentode vacuumtube input amplifier while the other channel used the common 12AX7triode vacuum tube as its input amplifier. The two channels hadsignificantly different audio characteristics, which was primarily dueto the higher-gain characteristics of the EF-86 pentode vacuum tube.

Selection of the channels was accomplished simply by choosing whichinput jack the guitar accessed and, unlike many of today's amplifiers,the channels were not able to be preset and foot switch selected inorder to readily access the different sounds provided by each channel(e.g, a cleaner sound using the 12AX7 triode vacuum tube and one morecapable of being overdriven via the higher-gain EF-86 pentode vacuumtube).

Even when vacuum tubes were mainstream components, the EF-86 pentodevacuum tube (a.k.a. 6267) was notoriously noisy and unreliable.Presently the EF-86 pentode vacuum tube is also rare and expensive, asare the vintage amplifiers that used them. Accordingly, there is a needto provide the desirable gain characteristics of the EF-86 pentodevacuum tube, while overcoming its associated problems of noise, failureand expense.

BRIEF DESCRIPTION OF THE DRAWINGS

Various ones of the appended drawings merely illustrate exampleembodiments of the present disclosure and are not intended to limit itsscope to the illustrated embodiments. On the contrary, these examplesare intended to cover alternatives, modifications, and equivalents asmay be included within the scope of the disclosure.

FIG. 1 is a circuit diagram of an amplifier input channel using a vacuumtube pentode configuration.

FIG. 2 is a circuit diagram of an amplifier input channel using a singlevacuum tube triode configuration.

FIG. 3 is a circuit diagram of an amplifier input channel using twovacuum tube triodes operating in a parallel configuration.

FIG. 4 is a circuit diagram of a configurable amplifier input channelusing two vacuum tube triodes, according to some example embodiments.

FIG. 5 is a circuit diagram of a configurable amplifier input channelusing two vacuum tube triodes, according to some example embodiments.

FIG. 6 is a block diagram of an amplifier including a configurableamplifier input channel, according to some example embodiments

DETAILED DESCRIPTION

Reference will now be made in detail to specific example embodiments forcarrying out the inventive subject matter of the present disclosure. Inthe following description, specific details are set forth in order toprovide a thorough understanding of the subject matter. It shall beappreciated that embodiments may be practiced without some or all ofthese specific details.

Disclosed is a configurable dual vacuum tube triode amplifier thatprovides for varying tonal characteristics. An input channel of theamplifier (e.g., amplifier preamp) utilizes two vacuum tube triodesresiding within either a single dual triode vacuum tube, such as the12AX7, or within separate vacuum tubes, such as two single triode vacuumtubes or two dual triode vacuum tubes, to provide desired tonalcharacteristics for the amplifier. The amplifier allows for thearrangement of the two vacuum tube triodes to be modified to achievevarying tonal characteristics, such as by providing for varying gainlevels. For example, the amplifier may provide for one arrangement ofthe two vacuum tube triodes to provide the higher gain and resultingtonal characteristics of a vacuum tube pentode configuration, which istypically provided by a pentode vacuum tube such as the EF-86. Theamplifier may also provide another arrangement of the vacuum tubetriodes to provide the lower gain and resulting tonal characteristics oftwo vacuum tube triodes operating in a parallel configuration or asingle vacuum tube triode configuration.

To achieve tonal characteristics nearly identical to the tonalcharacteristics provided by a vacuum tube pentode configuration, the twovacuum tube triodes are arranged in a cascode configuration. In acascode configuration, the plate element of one vacuum tube triode isconnected to the cathode of the other vacuum tube triode. Accordingly,the signal voltage of one vacuum tube triode modulates the currentflowing to the other vacuum tube triode, which may provide an increasein gain, similar to the increase in gain provided by a vacuum tubepentode configuration. The cascode configuration is little known andrarely used in the field of electronics as a whole, and it has not beenused in the commercial field of instrument amplification to increase thegain provided by triode vacuum tubes, as described in the presentdisclosure. The increase in gain provided by configuring vacuum tubetriodes in a cascode configuration achieves the desired tonalcharacteristics of a pentode configuration.

The varying arrangements of the two vacuum tube triodes may beaccomplished using electronic switches implemented within the inputchannel circuit of the amplifier. The electronic switches may be anytype of electronic switch that is capable of coupling and decouplingelectronic components within a circuit. For example, the electronicswitch may be an electronic component configured to disconnect orconnect a conducting path in an electronic circuit to interrupt ordivert the electrical current from one conductor to another. As anotherexample, the varying arrangements of the two vacuum tube triodes may beaccomplished via two separately wired input channel circuits, which mayeach be accessed separated using different input jacks.

The amplifier additionally includes a user configurable switchingcomponent that can be positioned in various positions to modify thearrangement of the two vacuum tube triodes in the input channel circuitof the amplifier. For example, the user configurable switching componentmay be a foot switch, knob, toggle switch, or the like. As anotherexample, the user configurable switching component may be two separateinput jacks to which an instrument cable may be connected.

A user may position the user configurable switching component into adesired position to modify the arrangement of the vacuum tube triodes,thereby changing the tonal characteristics provided by the amplifier.For example, the user may modify the position of the user configurableswitching component to cause a change in state of the electronicswitches implemented within the input channel circuit of the amplifier,thereby causing a change to the arrangement of the vacuum tube triodes.For example, the user configurable switching component may be positionedin a first position to arrange the vacuum tube triodes in a cascodeconfiguration providing tonal characteristics of a vacuum tube pentodeconfiguration. The user configurable switching component may also bepositioned in a second position to arrange the vacuum tube triodes in asingle vacuum tube triode configuration or as two vacuum tube triodesoperating in a parallel configuration to achieve the corresponding tonalcharacteristics.

This configurable design allows for commonly available, quiet, andreliable triode vacuum tubes, such as the 12AX7, to be used in place ofpentode vacuum tubes to achieve the tonal characteristics provided by avacuum tube pentode configuration, thereby addressing the shortcoming ofprevious amplifiers that used the rare and problematic EF-86 vacuumtube, such as the historic VOX amps. That is, the amplifier uses vacuumtube triodes arranged in a cascode configuration in place of a pentodevacuum tube to achieve a nearly identical tonal characteristic, whilealso providing for easy switching between separate tonal characteristicsusing a user configurable switching component (e.g., foot switch). Theseprovided benefits are of paramount importance for amplifiermanufacturers by offering economy, reliability, versatility andavailability while accurately delivering the desired musicalcharacteristics of vintage amplifiers.

FIG. 1 is a circuit diagram of an amplifier input channel 100 using avacuum tube pentode configuration. As shown in FIG. 1, the amplifierinput channel 100 includes a vacuum tube pentode 102, as found in apentode vacuum tube such as the EF-86. The vacuum tube pentode 102includes a cathode element 104 connected to ground 106 through a biasingresistor 108 and a bypass capacitor 110. A control grid 112 receivesincoming instrument (e.g., guitar) signal voltage via an input jack 114and includes a grid leak resistor 116 to maintain a zero-direct current(DC) voltage on the control grid 112.

High DC voltage at a terminal 118 feeds a load resistor 120 connected tothe plate element 122 of the vacuum tube pentode 102, and thefluctuations in DC voltage across load resistor 120 comprise theamplified signal. A coupling capacitor 124 blocks high DC voltage andallows only the amplified signal to proceed as output.

The vacuum tube pentode 102 includes a screen grid element 126 thatreceives a high DC voltage from the terminal 118 through a resistor 128and is bypassed to a ground 106 through a capacitor 130. A suppressorgrid 132 connects to the cathode element 104 in customary fashion. Thevacuum tube pentode 102 offers a significantly higher amplifying factor,or gain, than provided by a vacuum tube triode and that extra gain isthe defining tonal characteristic of the amplifier input channel 100using the vacuum tube pentode 102.

FIG. 2 is a circuit diagram of an amplifier input channel 200 using asingle vacuum tube triode 202, such as may be found in a single triodevacuum tube or a dual triode vacuum tube (e.g., 12AX7). The vacuum tubetriode 202 includes a cathode element 204 that is connected to ground206 via a resistor 208. A bypass capacitor 210 increases the gain anddetermines the low frequency roll off curve. A control grid 212 of thevacuum tube triode 202 receives signal from an electric instrumentthrough an input terminal 214. a grid leak resistor 216 maintains zeroDC voltage at control grid 212, thereby preventing static charging ofthe control grid 212.

High DC voltage at a terminal 218 is fed through a load resistor 220 tothe triode plate element 222 of the vacuum tube triode 202, and thefluctuations in DC voltage across the load resistor 220 comprise theamplified signal. A coupling capacitor 224 blocks high DC voltage andallows only the signal voltage fluctuations to pass through to theoutput.

FIG. 3 is a circuit diagram of an amplifier input channel 300 usingmultiple vacuum tube triodes 302, 304, such as (e.g., vacuum tube triode302 and vacuum tube triode 304) operating in a parallel. The vacuum tubetriodes 302, 304 may be encompassed within a single dual triode vacuumtube, such as a 12AX7, or within two separate vacuum tubes, such as twosingle triode vacuum tubes or two dual triode vacuum tubes. FIG. 3represents a similar circuit as shown in FIG. 2, but with two vacuumtube triodes 302, 304 operating in parallel, rather than a single vacuumtube triode 202 operating alone, as shown in FIG. 2. This may provide asonic improvement and/or lower noise compared to an amplifier inputchannel 200 that utilizes a single vacuum tube triode 202 performing thesame function. There is, however, no appreciable increase in gainbetween the amplifier input channel 300 shown in FIG. 3 and theamplifier input channel 200 shown in FIG. 2.

Although some component values may be altered to accommodate theincrease in current due to two vacuum tube triodes 302, 304 operating inparallel, the circuit is otherwise identical to that of FIG. 2. As shownin FIG. 3 the cathodes 306, 308 of the vacuum tube triodes 302, 304 areconnected together and biased and coupled to ground 310 through aresistor 312 and bypass capacitor 314. The control grids 316, 318 of thevacuum tube triodes 302, 304 are connected together and receive signalfrom an input terminal 320. A grid leak resistor 322 is provided toremove static charges from the control grids 316, 318 in standardfashion.

High DC voltage at a terminal 324 is fed through load resistor 326 tothe plate elements 328, 330 of the two vacuum tube triodes 302, 304. Acoupling capacitor 332 blocks high DC voltage and conducts the signalvoltage to the output.

FIG. 4 is a circuit diagram of a configurable amplifier input channel400 using two vacuum tube triodes 402, 404, according to some exampleembodiments. The vacuum tube triodes 402, 404 may be encompassed withina single dual triode vacuum tube, such as a 12AX7, or within twoseparate vacuum tubes, such as two single triode vacuum tubes or twodual triode vacuum tubes.

As shown in FIG. 4, the configurable amplifier input channel 400 allowsfor an arrangement of the two vacuum tube triodes 402, 404 to bemodified to provide varying tonal characteristics of an amplifier. Forexample, the two vacuum tube triodes 402, 404 can be arranged in acascode configuration, as shown by the arrows in the switching devicesS1, S2, S3, to achieve a tonal characteristic that is nearly identicalto the amplifier input channel 100 shown in FIG. 1 that uses a singlevacuum tube pentode 102. Alternately, the two vacuum tube triodes 402,404 can be arranged in a parallel configuration, as shown by the dashedlines at the switching devices S1, S2, S3, to achieve the tonalcharacteristics of the amplifier input channel 300 shown in FIG. 2 thatuses two vacuum tube triodes 302, 304 operating in a parallelconfiguration.

The configurable amplifier input channel 400 includes electronicswitches S1, S2, S3 that allow for the varying arrangement of the twovacuum tube triodes 402, 404. For example, a state of the electronicswitches S1, S2, S3 may be set into a first state as shown by the arrowsin the electronic switches S1, S2, S3 in which the two vacuum tubetriodes 402, 404 are arranged in a cascode configuration. Alternatively,the state of the electronic switches S1, S2, S3 may be set in a secondstate as shown by the dashed in the electronic switches S1, S2, S3, inwhich the two vacuum tube triodes 402, 404 are arranged in a parallelconfiguration.

The state of the electronic switches may be modified using a userconfigurable switching component, such as a footswitch, that can bepositioned into multiple positions. For example, the user configurableswitching component may be positioned into a first position to cause thefirst state of the electronic switches as shown by the arrows in theswitching devices S1, S2, S3, thereby causing the two vacuum tubetriodes 402, 404 to be arranged in a cascode configuration.Alternatively, the user configurable switching component may beconfigured into a second position to cause the second state of theelectronic switches as shown by the dashed lines in the switchingdevices S1, S2, S3, thereby causing the two vacuum tube triodes 402, 404to be arranged in a parallel configuration. Accordingly, a user of anamplifier that includes the configurable amplifier input channel 400 mayuse the user configurable switching component to easily change thearrangement of the two vacuum tube triodes 402, 404 to cause acorresponding change in the tonal characteristics of the amplifier.

As shown in FIG. 4, a cathode element 406 of the input vacuum tubetriode 402 is biased and connected to a ground 410 by a resistor 412. Acathode bypass capacitor 414 performs the usual duties of increasinggain and tailoring the frequency response. The control grid 416 of theinput vacuum tube triode 402 receives signal voltage from the inputterminal 420 and uses a grid leak resistor 422 to maintain a zero DCvoltage at the control grid 416. The portions of the configurableamplifier input channel 400 discussed in this paragraph are similar tothe amplifier input channel 200 shown in FIG. 2.

In contrast to the amplifier input channel 200 shown in FIG. 2, however,the plate element 424 of the input vacuum tube triode 402 is connectedvia the electronic switches S1, S2 to a cathode 408 of the upper vacuumtube triode 404 where the signal voltage provided by the input vacuumtube triode 402 modulates the current flowing through the upper vacuumtube triode 404. Modulating the current flowing through the upper vacuumtube triode 404 in this manner can be used to provide an increase ingain.

To achieve this, the control grid 418 of the upper vacuum tube triode404 is biased from high DC voltage at terminal 428 through a voltagedivider comprising a series resistor 430 and a shunt resistor 432. Thecontrol grid 418 of the upper vacuum tube triode 404 is bypassed for ACsignals by a capacitor 434 to ground 436. The plate element 426 of theupper vacuum tube triode vacuum tube 404 receives high DC voltage fromthe terminal 428 and voltage amplification occurs across a plate loadresistor 436 in the usual fashion. A DC blocking capacitor 438 couplesamplified signal to provide an output of the two vacuum tube triodes402, 404 arranged in the cascode configuration.

Alternately, when the electronic switches S1, S2, S3 are in a state asshown by dashed lines in FIG. 4, the two vacuum tube triodes 402, 404are arranged in a parallel configuration, similar to the amplifier inputchannel 300 as shown in FIG. 3. In this state, a first electronic switchS1 connects the plate element 424 of the input vacuum tube triode 402 tothe plate element 426 of the upper vacuum tube triode 404, a secondelectronic switch S2 connects the cathode element 406 of the inputvacuum tube triode 402 to the cathode 408 of the upper vacuum tubetriode 404, and a third electronic switch S3 connects together thecontrol grid 416 of the input vacuum tube triode 402 to the control grid418 of the upper vacuum tube triode 404, and isolates the control grid418 of the upper vacuum tube triode 404 from the bypass capacitor 434and the voltage divider 430, 432 fed by the high voltage terminal 428.

FIG. 5 is a circuit diagram of a configurable amplifier input channel500 using two vacuum tube triode vacuum tubes 402, 404, according tosome example embodiments. As the circuit shown in FIG. 5 is nearlyidentical to the circuit shown in FIG. 4, the discussion of FIG. 5 willfocus primarily on the differences between the two circuits.

The configurable amplifier input channel 500 shown in FIG. 5 allows foran arrangement of the two vacuum tube triodes 402, 404 to be modified toachieve varying tonal characteristics. Similar to the configurableamplifier input channel 400 shown in FIG. 4, the two vacuum tube triodes402, 404 shown in FIG. 5 can be arranged in a cascode configuration,when the electronic switches S1, S2, S3 are in a first state asrepresented by arrows in the electronic switches S1, S2, S3. Whenarranged in the cascode configuration, the configurable amplifier inputchannel 500 achieves a tonal characteristic that is nearly identical tothe amplifier input channel 100 shown in FIG. 1 that uses a singlevacuum tube pentode 102.

In contrast to the configurable amplifier input channel 400 shown inFIG. 4, the two vacuum tube triodes 402, 404 shown in FIG. 5 can also bearranged in a single vacuum tube triode configuration, when theelectronic switches S1, S2, S3 are in a second state as represented bythe dashed lines at the electronic switches S1, S2, S3. When arranged inthe single vacuum tube triode configuration, the configurable amplifierinput channel 500 achieves the tonal characteristic of the amplifierinput channel 200 shown in FIG. 2 that uses a single vacuum tube triode202 operating alone.

As with the configurable amplifier input channel 400 shown in FIG. 4,the arrangement of the two vacuum tube triodes 402, 404 may be modifiedusing a user configurable switching component, such as a footswitch,that can be positioned into multiple positions. For example, the userconfigurable switching component can be positioned into a first positionto cause the electronic switches S1, S2, S3 to be in the state shown bythe arrows, thereby arranging the two vacuum tube triodes 402, 404 in acascode configuration. Alternatively, the user configurable switchingcomponent can be positioned into a second position to cause theelectronic switches S1, S2, S3 to be in the state as shown by the dashedlines, thereby arranging the two vacuum tube triodes 402, 404 in asingle vacuum tube triode configuration, similar to the amplifier inputchannel 200 as shown in FIG. 2.

The electronic switches S1, S2, S3 being in the state as shown by thedashed lines, connects the plate element 424 of the input vacuum tubetriode 402 to the terminal 428 through a load resistor 502 such thatinput vacuum tube triode 402 operates as a single-vacuum tube triodeamplifier (like that of FIG. 2) and has its output coupled throughblocking capacitor 504. The upper vacuum tube triode 404 is then unusedand available for a separate application. That is, the upper vacuum tubetriode 404 is not used within the circuit shown in FIG. 5 in which theinput vacuum tube triode 402 remains in use. However, the upper vacuumtube triode 404, when unused within the circuit shown in FIG. 5 may beused for another purpose. That is, the upper vacuum tube triode 404 maybe included in another circuit (not shown) within the amplifier. In thistype of embodiment, the upper vacuum tube triode 404 and the inputvacuum tube triode 402 would be used in different circuits such that theinput vacuum tube triode 402 would be used and the upper vacuum tubetriode 404 would not be used within the circuit shown in FIG. 5, whilethe upper vacuum tube triode 404 would be used and the input vacuum tubetriode 402 would not be used within the other circuit.

The ability to modify the arrangement of the two vacuum tube triodes402, 404, as shown by the varying states of the electronic switches S1,S2, S3 in FIGS. 4 and 5, allows for the arrangement of the two vacuumtube triodes 402, 404 to be easily modified using a user configurableswitching component, such as a foot switch. This provides a modernbenefit to a legacy amplifier's performance. Further benefits ofeconomy, reliability and noise reduction are also achieved whileutilizing commonly available triode vacuum tubes, such as the 12AX7.While FIG. 4 and FIG. 5 show two embodiments of the present invention,these are not meant to be limiting. Minor deviations to the shownembodiments may circumvent some specifics, while providing theequivalent of its essence.

FIG. 6 is a block diagram of an amplifier 600 including a configurableamplifier input channel (e.g., shown in FIGS. 4 and 5), according tosome example embodiments. As shown, the amplifier 600 includes a preamp602, a power amp 604, a speaker 606, and a user configurable switchingcomponent 608. The preamp 602 receives an input signal from anelectronic instrument, that is connected to the amplifier 600. Forexample, the input signal may be received from an electric guitarconnected to the amplifier 600 via an instrument cable.

The preamp includes two vacuum tube triodes 402, 404, which can bearranged into a cascode configuration or a normal vacuum tube triodeconfiguration, such as two vacuum tube triodes 402, 404 operating in aparallel configuration (as shown in FIG. 4) or a single vacuum tubetriode configuration (as shown in FIG. 5).

The user configurable switching component 608 is connected to the preampand can be used to modify the arrangement of the two vacuum tube triodes402, 404. For example, the user configurable switching component 608 maybe positioned into a first position to cause the two vacuum tube triodes402, 404 to be arranged in a cascode configuration, and the userconfigurable switching component 608 may be positioned into a secondposition to cause the two vacuum tube triode vacuum tubes 402, 404 to bearranged in either a parallel configuration or a single vacuum tubetriode vacuum tube configuration. The user configurable switchingcomponent 608 may be any type of component capable of being configuredinto multiple positions, such as a foot switch, knob, toggle switch,multiple input jacks, or the like.

The preamp 602 pass the input signal through the arrangement of the twovacuum tube triodes 402, 404 to generate an output signal. The preamp602 provides the output signal to the power amp 604, which amplifies theoutput signal to result in an amplified output signal. The power amp 604then provides the amplified output signal to the speaker 606, whichoutputs audio sound based on the amplified output signal generated bythe power amp 606.

Although the amplifier 600 shown in FIG. 6 includes a preamp 602, poweramp 604 and a speaker 606, this is just one embodiment and is not meantto be limiting. In some embodiments, the amplifier 600 may not includeeither the power amp 604 and/or the speaker 606. Further, the amplifier600 may include any number of speakers 606. Finally, the preamp 602,power amp 604, and speaker 606 may be encompassed within a singlephysical component, such as a combo amplifier, or alternatively,encompassed within multiple physical components, such as a separateamplifier head and amplifier speaker cabinet.

Language

Although the embodiments of the present invention have been describedwith reference to specific example embodiments, it will be evident thatvarious modifications and changes may be made to these embodimentswithout departing from the broader scope of the inventive subjectmatter. Accordingly, the specification and drawings are to be regardedin an illustrative rather than a restrictive sense. The accompanyingdrawings that form a part hereof show by way of illustration, and not oflimitation, specific embodiments in which the subject matter may bepracticed. The embodiments illustrated are described in sufficientdetail to enable those skilled in the art to practice the teachingsdisclosed herein. Other embodiments may be used and derived therefrom,such that structural and logical substitutions and changes may be madewithout departing from the scope of this disclosure. This DetailedDescription, therefore, is not to be taken in a limiting sense, and thescope of various embodiments is defined only by the appended claims,along with the full range of equivalents to which such claims areentitled.

Such embodiments of the inventive subject matter may be referred toherein, individually and/or collectively, by the term “invention” merelyfor convenience and without intending to voluntarily limit the scope ofthis application to any single invention or inventive concept if morethan one is in fact disclosed. Thus, although specific embodiments havebeen illustrated and described herein, it should be appreciated that anyarrangement calculated to achieve the same purpose may be substitutedfor the specific embodiments shown. This disclosure is intended to coverany and all adaptations or variations of various embodiments.Combinations of the above embodiments, and other embodiments notspecifically described herein, will be apparent, to those of skill inthe art, upon reviewing the above description.

All publications, patents, and patent documents referred to in thisdocument are incorporated by reference herein in their entirety, asthough individually incorporated by reference. In the event ofinconsistent usages between this document and those documents soincorporated by reference, the usage in the incorporated referencesshould be considered supplementary to that of this document; forirreconcilable inconsistencies, the usage in this document controls.

In this document, the terms “a” or “an” are used, as is common in patentdocuments, to include one or more than one, independent of any otherinstances or usages of “at least one” or “one or more.” In thisdocument, the term “or” is used to refer to a nonexclusive or, such that“A or B” includes “A but not B,” “B but not A,” and “A and B,” unlessotherwise indicated. In the appended claims, the terms “including” and“in which” are used as the plain-English equivalents of the respectiveterms “comprising” and “wherein.” Also, in the following claims, theterms “including” and “comprising” are open-ended; that is, a system,device, article, or process that includes elements in addition to thoselisted after such a term in a claim are still deemed to fall within thescope of that claim.

What is claimed is:
 1. An amplifier comprising: a first vacuum tubetriode; a second vacuum tube triode; and a user configurable switchingcomponent that can be positioned into at least a first position and asecond position to modify an arrangement of the first vacuum tube triodeand the second vacuum tube triode to provide varying tonalcharacteristics of the amplifier, the first position arranging the firstvacuum tube triode and the second vacuum tube triode in a cascodeconfiguration to achieve a tonal characteristic of a vacuum tubepentode, and the second position arranging the first vacuum tube triodeand the second vacuum tube triode in a parallel configuration to achievea tonal characteristic of two vacuum tube triodes operating in parallel.2. The amplifier of claim 1, wherein positioning the user configurableswitching component into the first position couples a plate element ofthe first vacuum tube triode to a cathode of the second vacuum tubetriode.
 3. The amplifier of claim 2, wherein signal voltage of the firstvacuum tube triode modulates a current flowing to the second vacuum tubetriode via a connection between the plate element of the first vacuumtube triode and the cathode of the second vacuum tube triode.
 4. Theamplifier of claim 3, wherein the signal voltage of the first vacuumtube triode modulates the current flowing to the second vacuum tubetriode to cause an increase in gain.
 5. The amplifier of claim 2,wherein positioning the user configurable switching component into thesecond position decouples the plate element from the first vacuum tubetriode and the cathode of the second vacuum tube triode.
 6. Theamplifier of claim 5, wherein positioning the user configurableswitching component into the second position couples the plate elementof the first vacuum tube triode to a plate element of the second vacuumtube triode.
 7. The amplifier of claim 1, wherein the user configurableswitching component is a foot switch.
 8. The amplifier of claim 1,wherein the first vacuum tube triode and the second vacuum tube triodeare encompassed within a single 12AX7 vacuum tube.
 9. The amplifier ofclaim 1, wherein the first vacuum tube triode and the second vacuum tubetriode are encompassed within two separate vacuum tubes.
 10. Theamplifier of claim 9, further comprising: a preamp including the firstvacuum tube triode and the second vacuum tube triode, the preampconfigured to receive an input signal and pass the input signal throughthe arrangement of the first vacuum tube triode and the second vacuumtube triode to generate an output signal; a power amp configured toamplify the output signal generated by the preamp, resulting in anamplified output signal; and a speaker configured to output audio soundbased on the amplified output signal from the power amp.
 11. Anamplifier comprising: a first vacuum tube triode; a second vacuum tubetriode; and a user configurable switching component that can bepositioned into at least a first position and a second position tomodify an arrangement of the first vacuum tube triode and the secondvacuum tube triode to provide varying tonal characteristics of theamplifier, the first position arranging the first vacuum tube triode andthe second vacuum tube triode in a cascode configuration to achieve atonal characteristic of a vacuum tube pentode, and the second positionarranging the first vacuum tube triode and the second vacuum tube triodein a single vacuum tube triode configuration to achieve a tonalcharacteristic of a single vacuum tube triode operating alone.
 12. Theamplifier of claim 11, wherein positioning the user configurableswitching component into the first position couples a plate element ofthe first vacuum tube triode to a cathode of the second vacuum tubetriode.
 13. The amplifier of claim 12, wherein signal voltage of thefirst vacuum tube triode modulates a current flowing to the secondvacuum tube triode via a connection between the plate element of thefirst vacuum tube triode and the cathode of the second vacuum tubetriode.
 14. The amplifier of claim 13, wherein the signal voltage of thefirst vacuum tube triode modulates the current flowing to the secondvacuum tube triode to cause an increase in gain.
 15. The amplifier ofclaim 12, wherein positioning the user configurable switching componentinto the second position decouples the plate element of the first vacuumtube triode from the cathode of the second vacuum tube triode, andcouples the plate element of the first vacuum tube triode to a plateload resistor connected to a high voltage terminal.
 16. The amplifier ofclaim 15, wherein positioning the user configurable switching componentinto the second position results in the second vacuum tube triode beingunused within a first circuit that includes the first vacuum tubetriode, and the second vacuum tube triode being used within a secondcircuit that does not include the first vacuum tube triode.
 17. Theamplifier of claim 11, wherein the user configurable switching componentis a foot switch.
 18. The amplifier of claim 11, wherein the firstvacuum tube triode and the second vacuum tube triode are encompassedwithin a single 12AX7 vacuum tube.
 19. An amplifier comprising: a firstvacuum tube triode and a second vacuum tube triode implemented within anelectronic circuit; and at least one electronic switch implementedwithin the electronic circuit that can be switched between a first stateand a second state to modify an arrangement of the first vacuum tubetriode and the second vacuum tube triode to provide varying tonalcharacteristics of the amplifier, the first state arranging the firstvacuum tube triode and the second vacuum tube triode in a cascodeconfiguration to achieve a tonal characteristic of a vacuum tubepentode, and the second state arranging the first vacuum tube triode andthe second vacuum tube triode in either a parallel configuration toachieve a tonal characteristic of two vacuum tube triodes operating inparallel or a single vacuum tube triode configuration to achieve a tonalcharacteristic of a single vacuum tube triode operating alone.
 20. Theamplifier of claim 1, further comprising: a user configurable switchingcomponent that can be positioned into at least a first position and asecond position to modify the state of the at least one electronicswitch, a first position of the user configurable switching componentcausing the first state of the at least one electronic switch and thesecond position of the user configurable switching component causing thesecond state of the at least one electronic switch.